Variant Lib

Fixes

• Potentially fixed crashes involving reused entity render states and variants stored in those.
• Improved memory usage on clients by implementing equals and hashCode in internal Variant Model classes.
• Updated references to GitHub to utilize Greenhouse Forgejo instead.

Breaking Changes

This update contains a breaking change to the base Variant Model objects for mod developers, they are now abstract classes rather than an interface. Please read the above fix for more information.